The world today has a strong democratic core shaped by American ingenuity, sacrifice, and spirit. But on the periphery are many unstable and dangerous places, where terrorists seek to impose a medieval dark age. As we learned so brutally and so personally, we do face a new threat. But we also face a renewed choice – between isolation in a perilous world, which I believe is impossible in any event, and engagement to shape a safer world which is the urgent imperative of our time.